class_docstr: Holds utility methods to work with a tokenized text and entity spans.
  
  Spans must be tuples containing the label (str), start char idx (int), and end char idx (int).
  
  Args:
      text: The text the spans refer to.
      tokens: The tokens of the text.
docstr: The token index to start/end char index mapping.
docstr_tok: ["The","token","index","to","start\/end","char","index","mapping","."]
code: def token_to_char_idx(self) -> Dict[int, Tuple[int, int]]:
      """The token index to start/end char index mapping."""
      return self._token_to_char_idx
  
file_path: argilla/src/argilla/utils/span_utils.py
imports: from typing import Dict, List, Optional, Tuple
label_desc: Use image node_id 4 for calling the SpanUtils obj's underlying member method code with example usage: obj.token_to_char_idx() and returns: self